1. Field of the Invention
The present invention relates to airplanes in general, and, in particular, to airplanes having particular wing features adapted so as to achieve an airfoil design convertible between high-lift and high-speed configurations.
2. Description of the Prior Art
In the art of aircraft and airfoil design the requirements of high-lift and low-drag are very often in conflict, particularly in airplanes designed for high-speed flight. Aircraft designed for flight at such high speeds are required to have low drag in order to obtain maximum efficiency in achieving such high speeds, but it is also desirous for such aircraft to have a capability for a relatively high amount of lift so that they can take-off and land with low speeds in relatively short distances. These conflicting objects have resulted in a wide variety of "compromise" wing designs which are designed to provide a significant amount of lift while reducing drag as much as possible, and have resulted in the designing of airplanes with variable pitch swept-back wings which may be pivoted toward and away from the aircraft fuselage to increase or decrease drag and lift alternatively. A variety of flap systems have been designed which retract into fixed wing aircraft, thus changing the wing chord length and thickness. These devices are extremely complicated, heavy, and are impractical for supersonic aircraft with thin wings requiring separate drag producing tail surfaces to maintain control of the aircraft during both high and low speed flight. Present delta shaped wings rely upon "incidental" or "compression" lift obtained in flight at high angles of attack to take off or land the aircraft with reduced speed.
The prior art is generally cognizant of the use of variable airfoils to help achieve greater lift in fixed wing aircraft. Thus, for example, U.S. Pat. No. 1,670,852, No. 2,112,154, and No. 3,179,354 disclose aircraft having wings which are, in some respect or another, changeable in their lift and/or drag configurations. Examples are also known, such as that shown in U.S. Pat. No. 1,913,169 of airfoil designs designed to enhance lift and the angle of attack of the aircraft wing to the airflow. Aircraft without tails are known such as the example of the tailless aircraft shown in U.S. Pat. No. 2,412,646. Fixed wing aircraft utilizing more than one flap to achieve high-lift are also known such as the examples shown in U.S. Pat. No. 3,853,289 and No. 4,117,996. No examples of delta wing aircraft with externally actuated multi-flap arrangements with multi-positionable concomitant stabilizers were seen in an extensive search of a number of sub-classes under class 244, Aeronautics.